Abstract: This paper presents an approximate analytic method for the stiffened torispherical shell with opening under uniform external pressure, that is, the equivalent spherical shell method. Non-spherical factor is defined to reflect the effect of the shell. Equivalent membrane thickness and equivalent bending thickness are used to describe the effect of the stiffeners, the nominal stress and tangent module of the material are used to express the degree of plasticity of the shell. The numerical results indicate that the method presented in the paper has better precision and can be used in engineering.